OF SOUTHEEN INDIA. 43 



of the original materials. Some more species I shall have to mention when speaking of Fholadomya 

 and Panopaa. It is to be hoped that the attention of palffioutologists will be directed more to the 

 genus PoroniT/a, than has been hitherto the casCj for it is really a very important genus among 

 mesozoic Pelecypoda. 



Under Mt/a a few species from cretaceous rocks have been described by older authors, but none 

 of them have been proved to belong to that genus. The same is, strictly speaking, the ease with 

 Jurassic and a few palteozoic species of the so-called Mya, for their determination as yet only depends 

 upon the external form, and seems in many cases a very doubtful one. 



Thus we have in the cretaceous deposits Corhula, Corhnlamella, Neara, Poromya, most probably 

 Corhdomya, and possibly Himella represented ; Spheniopsis, Eiccharls, Corburella, and Cnjptomya may 

 be shown to occur; but no such forms as Tugonia, Sphenia, Plati/odon, and even Mya are as yet 

 distinctly indicated. 



COUBULA, Brug., 1792, (see p. 35). 

 1. CoRBULA STRiATULOiDES, Forbes, PI. XVI, Ejgs. 13-14. 



1846. C. striaiuloides, Forb., Trans., Geol. Soc, Lond., VII, p. 141, pi. 18, fig. 14 — idem, auctorum. 

 1847.? C. cochlearia, d'Orbigny, Pal. of tlie voy. de 1' Astrolabe, pi. 5, figs. 14-17. 



C. testa ohlonga, j^ostice breviter ac rectinscule caudata, crassa, convexn, 

 nmbonibus incurvis, fere centralUer sitis instructa ; valvula clextra majoi'i, postice 

 obliqtte carinata, concenti'ice confertim striata ; valcula sinistra minori, prope peri- 

 pheriam striis crassiusculis jjnedita. 



Height of the larger valve : its length ... ... ... 066 



Thickness of shell : „ ... ... ... 0-44 



The solid structure, tlie great convexity of the right valve, and its short poste- 

 rior prolongation readily distinguish this species from the European C. striatula, 

 and the small height from C. sub-striatula. The right valve is much more solid 

 than the left one ; it also has the margins strongly bent in towards the latter, which 

 is thinner, considerably smaller, but a little more coarsely striated than the 

 right one. The species is very much like the recent C sulcata, Lam., from 

 Senegal. 



D'Orbigny's C. cochlearia is most probably the same species as C. striattdoides, 

 though the figures do not correspond very well. The coarser striation of the left 

 valve is distinctly shown ; but the right valve of striattdoides is finely striated, 

 while D'Orbigny's figm'e represents it equally, or even more coarsely striated 

 than that of the left valve ; no such form occurs in our collection of the South 

 Indian cretaceous fossils. 



Locality. — In a light coloured sandstone south of Koloture ; rare. A similar 

 but flatter species occurs in the soft sandstones at Streepermatoor, but the specimens 

 are not sufficient for characterizing the species. 



Formation. — Trichinopoly group. 



